Field of the Invention
This invention pertains to vibratory devices of the type used in the bulk material handling industry. More particularly, this invention pertains to a rotary vibratory device having an eccentric weight that is supported by two radial bearings and comprises an electric motor extending axially between such bearings.
General Background
Vibratory devices are used throughout the bulk material handling industry for various purposes. Vibratory devices are often attached to bulk material transfer chutes and bulk material storage hoppers to prevent bulk material from clinging to the walls of such chutes and hoppers. Vibratory devices are also utilized on sifting or sorting screens to prevent larger material from clogging the sifting screens and to speed the flow of material passing through the screens.
A common type of vibratory device is the rotary vibratory motor, wherein one or more eccentric weights are rotationally driven by and rotate about an axis to thereby create a revolving oscillating force. Other types of vibratory devices include, but are not limited to, acoustical vibration devices, air driven rotary vibrators, and linear vibrators. The present invention pertains specifically to an electrically driven rotary vibratory device wherein one or more eccentric weights are rotationally driven about an axis (hereafter referred to simple as a rotary vibratory device).
Some rotary vibratory devices comprise two or more eccentric weights positioned on axially opposite sides of an electric motor. Typically, such devices comprise a pair of bearings, each positioned axially between one of the eccentric weights and the electric motor. Typically eccentric weights are mounted to a shaft that extends through the bearings and the motor. As such, the rotation of the eccentric weights of such motors exerts large bending moments on the shaft. That causes the shaft to deflect, which reduces the life of the bearings since the loads thereon are not purely radial. Additionally the diameter of the shaft and bearings of such motors are typically minimized so as to reduce fabrication costs and the radial diameter of the rotor, but must be large enough to handle the eccentric loads. As a result, the bearings of electrically driven rotary vibratory devices are often periodically replaced and drive the maintenance needs of such devices.